A tandem-type color laser printer, as a color printer using an electrophotography method, provided with a plurality of photoconductors and a plurality of developer cartridges are well known in the art. In the tandem type color laser printer, the plurality of photoconductors are arranged in parallel in correspondence with toners of four colors of yellow, magenta, cyan, and black. The plurality of developer cartridges are arranged in correspondence with the photoconductors so as to feed toners to the photoconductors.
A following developer cartridge is proposed as an example of a developer cartridge provided in such a tandem-type color laser printer. That is, the developer cartridge includes a developing roller and a feed roller brought into contact with the developing roller. When the developer cartridge is attached to a drum cartridge that rotatably supports the photosensitive drum, the developer cartridge is configured to be pressed elastically against a photosensitive drum such that the developing roller is brought into elastic press-contact with the photosensitive drum.
The developer cartridge has a bias electrode brought into contact with a relay electrode provided in the drum cartridge. The bias electrode is formed of a plate spring and has a protruding portion protruding outward in the width direction of the developer cartridge toward the relay electrode of the drum cartridge.
When the developer cartridge is mounted on the drum cartridge, the protruding portion of the bias electrode is brought into press-contact with the relay electrode of the drum cartridge.
As a result, bias voltage applied from a high voltage power supply provided in a main body casing is applied to the bias electrode of the developer cartridge through the relay electrode of the drum cartridge.